Bacteriological  Investigations 


OF  THE 


Iowa  State  College  Sewage. 


BULLETIN  No.  2 

By  L.  R.  WALKER. 


Reprint  from  Proceedings 
Iowa  Academy  of  Sciences,  1901 


DES  MOINES 

BERNARD  MURPHY,  STATE  PRINTER. 
1901. 


UNIVERSITY  OF  ILLINOIS 


LIBRARY 


BOOK 


CLASS 

WlS 


VOLUME 


*1  FosPfav.F 


\  BACTERIOLOGICAL  INVESTIGATION  OF  THE  IOWA 
STATE  COLLEGE  SEWAGE. 

V)  -  - 

ft 

L.  R.  WALKER. 


INTRODUCTION. 

As  an  introduction  to  the  consideration  of  the  Iowa 
State  College  sewage,  the  kinds  of  sewage,  the  necessity  of 
disposal,  and  several  of  the  most  important  methods  with 
their  merits  and  disadvantages  will  be  discussed. 

It  has  been  my  object  in  the  following  paper  to  bring 
together  the  data  obtained  from  the  bacteriological 
analysis  of  the  college  sewage,  including  daily  samples 
from  the  effluent  and  weekly  samples  from  the  manhole 
and  tank.  Together  with  this  data  are  given  the  daily 
temperatures  of  the  air  and  of  the  sewage,  at  the  time  of 
taking  samples;  also,  the  soil  temperatures,  which  were 
taken  once  a  week. 

Besides  this  data  it  has  seemed  desirable  to  give  the 
methods  employed  in  the  determination  of  the  number  of 
bacteria  per  cubic  centimeter  of  the  sewage. 

And  lastly,  a  partial  interpretation  of  the  results 
obtained,  has  been  attempted,  special  attention  having 
been  given  to  the  percentage  of  gas  producers  present  in 
the  manhole,  tank,  and  effluent,  and  to  the  fluctuations, 
during  the  different  days  and  seasons,  of  the  number  of 
bacteria  per  cubic  centimeter  in  the  samples  from  the 
manhole,  tank,  and  effluent.  The  determination  of  the 
species  of  bacteria  present  in  the  sewage  has  not  been 
attempted,  only  incidentally. 

From  a  sanitary  point  of  view  there  is  no  question  of 
more  vital  importance  than  the  proper  disposal  of  sewage. 
The  lack  of  such  disposal  brings  a  multitude  of  evils, 


o  l  O 

6  >>o 


—  2  — 


which  often  culminate  in  prolonged  illness,  or  even  death; 
not  only  is  waste  of  all  kiuds  a  menace  to  the  public 
health,  but  it  is  also  a  repulsive  sight  to  the  aesthetic 
tastes  of  any  civilized  community.  This  last  factor  alone 
would  make  sewage  disposal  a  question  of  considerable 
importance,  as  the  value  of  property  depends  to  a  consid¬ 
erable  extent  upon  its  attractiveness,  and  anything  which 
takes  away  from  its  good  appearance  deducts  from  its 
market  value. 

The  question  of  sewage  disposal  is  coming  to  be  recog¬ 
nized  by  the  officers  of  the  state  boards  of  health  in  the 
various  states.  Perhaps,  as  leaders  in  this  movement,  may' 
be  mentioned  Massachusetts,  Connecticut  and  Maryland. 
The  State  Board  of  Health  of  Iowa  (14),  in  its  annual 
report  for  1899,  called  especial  attention  to  the  almost  utter 
lack  of  adequate  means  of  sewage  disposal  in  the  small 
towns  and  cities  of  the  state,  and  urges  that  some  action 
be  taken  toward  securing  proper  sewage  disposal. 

In  considering  the  question  of  sewage  disposal  it  may  be 
well  to  define  what  is  meant  by  sewage.  Sewage,  accord¬ 
ing  to  Barwise  (3),  comes  from  the  Anglo-Saxon  word 
seon,  which  means  to  flow  down  and  includes  the  liquid 
contents  of  a  sewer.  Rafter  and*  Baker  (5),  however,  give 
sewage  as  including  not  only  the  combined  water  and 
waste  matters  flowing  in  sewers,  but  the  mixed  solids  and 
liquid  matter.  This  latter,  it  seems,  is  a  better  definition 
as  it  includes  the  solid  excreta  as  well  as  the  matter  in 
solution. 

The  kinds  of  sewage  will  necessarily  vary  with  the  im¬ 
posed  conditions.  The  most  common  may  well  be  termed 
domestic  sewage,  which  contains  kitchen  slops  and  all  the 
common  refuse  of  ordinary  dwellings.  Factory  sewage  is 
more  complex  in  most  cases,  depending,  of  course,  upon 
the  particular  kind  of  factory  under  consideration.  Pack¬ 
ing  house  sewage  would  hardly  come  in  this  category,  yet 
it  plays  a  very  important  part  in  sewage  disposal  on  ac¬ 
count  of  its  peculiar  constituents.  Surface  sewage,  if  such 
it  may  be  called,  is  composed  chiefly  of  water,  and  the 
washings  from  the  streets,  alleys,  etc.  City  sewage  being 


—  3  — 


essentially  a  compound  of  all  the  above  mentioned,  with 
the  addition  of  others  not  enumerated,  make  it  very  com¬ 
plex  and  hard  to  deal  with,  as  the  plan  adopted  must 
needs  be  one  which  takes  into  account  all  its  peculiarities 
and  treats  it  accordingly. 

After  what  has  been  written  on  the  subject  of  the 
necessity  of  sewage  disposal  it  seems  almost  needless  to 
try  to  add  anything  new.  Yet  it  may  be  of  interest  to 
make  a  brief  review  of  the  already  published  facts.  That 
sewage  is  a  source  of  contamination  and  disease  has  long 
been  established,  many  cases  of  typhoid  fever  have  been 
directly  traced  to  the  lack  of  proper  sewage  disposal  or  the 
contamination  of  drinking  water  with  sewage.  Barwise 
records  an  outbreak  of  typhoid  fever  at  Wesleyan  Univer¬ 
sity,  Middletown,  Conn.,  in  which  there  is  indisputable 
evidence  that  it  was  due  to  the  eating  of  oysters  which 
had  been  grown  in  water  contaminated  with  sewage.  He 
also  reports  an  interesting  case  of  sewage  contamination 
of  the  water  supply  at  Tees. 

Bacillus  typhosus  is  not  the  only  pathogenic  germ  found 
in  sewage  as  numerous  experiments  have  shown,  that 
Bacillus  anthracis ,  (1)  (the  Bacteridie  du  charbon,  of  the 
French)  not  only  lives  in  water  but  that  it  maintains  its 
vitality  for  some  time  is  well  know.  The  spirillum  of 
Asiatic  cholera  has  been  known  to  retain  its  vitality  in 
the  domestic  water  supply  of  Berlin  from  267  to  882  days. 
(15).  The  Bacillus  coli-communis  and  Bacillus  cloacae  while 
strictly  speaking  are  not  pathogenic  are  always  to  be 
regarded  with  suspicion  when  they  occur  in  water  as  they 
frequently  do.  (5).  Many  disease  germs  may  live  in 
sewage  for  a  short  time  and  be  propagated  there.  Thus  it 
can  be  readily  seen  that  polluted  water  is  a  possible  source 
for  almost  any  bacteriological  disease. 

It  is  a  fact  of  common  observation  that  sewage  pollution 
of  streams  is  detrimental  to  the  fish  it  contains,  and  indeed 
cases  are  recorded  where  the  entire  fish  life  of  a  stream  for 
a  given  distance  has  been  destroyed  by  sewage  pollution. 
A  case  of  this  kind  happened  in  our  own  state  a  few  years 
ago  at  Marshalltown. 


—  4  — - 


If  no  diseases  were  produced  by  unpurified  sewage,  the 
stench  arising  from  it  would  be  sufficient  reason  for  urging 
its  purification.  In  this  connection  it  may  be  well  to  state 
that  Dr.  L.  P.  Kinnicutt,  (15)  of  Polytechnic,  Boston,  in  a 
paper,  “Sewer  Air  and  Mistaken  Ideas  Regarding  It,”  main¬ 
tains  with  a  considerable  force  of  reason  that  it  is  not  as 
harmful  as  commonly  believed,  but  even  this  does  not  do 
away  with  the  fact  that  it  is  decidedly  disagreeable. 

Now  that  we  have  noticed  some  of  the  reasons  for  sew¬ 
age  purification  it  may  be  well  to  investigate  some  of  the 
various  means  by  which  it  may  be  accomplished.  In  a 
short  paper  it  is  impossible  to  go  into  details  of  all  the 
various  systems  or  indeed  to  even  consider  them  all.  So 
this  paper  will  be  confined  to  the  treatment  of  the  follow¬ 
ing  systems:  Natural  dilution,  sewage  farming,  chemical 
precipitation,  filtration  both  continuous  and  intermittent, 
the  septic  tank,  and  the  combination  of  several  of  these 
systems  into  combined  systems. 

The  natural  dilution  of  sewTage  can  hardly  be  called  a 
system,  and  yet  it  is  the  only  means  employed  in  the  vast 
majority  of  cases.  It  is  nothing  more  or  less  than  the  allow¬ 
ing  of  sewage,  to  flow  into  the  natural  waterways,  seas,  etc. 
In  this  way  the  concentrated  sewage  becomes  diluted 
(hence  the  derivation  of  the  name  applied)  and  nature  does 
the  rest.  If  it  were  not  for  the  fact  that  the  majority  of 
towns  and  cities  draw  their  water  supply  from  the  rivers 
on  which  they  are  situated,  in  some  few  cases  it  might  do 
very  well.  A  great  many  factors  must  be  considered  in 
determining  the  effectiveness  of  natural  dilution,  among 
which  the  most  important  are  the  rapidity  of  the  stream 
and  the  volume  of  water  that  it  carries.  As  all  the  rivers 
in  Iowa  are  relatively  small  and  unimportant  this  method 
cannot  be  considered  as  sufficient  in  itself  in  this  state. 

The  system  of  sewage  farming  has  been  employed  quite 
extensively  in  various  places,  but  is  not  commonly  consid¬ 
ered  as  a  success.  The  method  employed  is  similar  to  that 
used  in  .irrigation.  The  sewage  is  allowed  to  flow  through  a 
system  of  trenches  provided  with  flood  gates  so  that  the  flow 
can  be  controlled.  The  theory  is,  and  it  is  correct,  that  the 


—  5  — 

plants  of  the  fields  to  which  this  is  applied  will,  finally 
incorporate  it  into  their  own  tissues  after  it  has  been  decom¬ 
posed  by  bacteria.  As  can  be  readily  seen  such  a  system 
must  have  several  serious  disadvantages.  First,  granting 
that  sewage  farming  will  purify  the  sewage,  which  no  doubt 
can  be  done  to  a  greater  or  less  extent  owing  to  the  imposed 
conditions  it  is  still  doubtful  whether  or  not  it  could  be 
carried  on  successfully  in  a  great  majority  of  cases.  In  the 
first  place  the  land  must  be  of  such  a  character  as  to  per¬ 
mit  of  the  irrigation  system;  secondly,  if  the  sewage  were 
applied  continuously,  it  would  be  disastrous  to  the  crops, 
killing  them  out  as  well  as  preventing  the  nitrification  of 
the  sewage  by  limiting  the  supply  of  oxygen  to  the  soil.  In 
the  third  place,  the  amount  of  desirable  land  required  would 
in  many  cases  be  very  expensive  if  it  could  be  obtained  at 
all.  Mr.  B.  S.  Brundell,  M.  Inst.  C.  E.,  who  has  constructed 
many  sewer  farms,  among  them  a  farm  at  Dorchester,  Eng¬ 
land,  which  is  one  of  the  most  successful  from  a  sanitary 
point  of  view,  wrote  as  follows:  “Sewage  if  properly  ap¬ 
plied  to  land  may  be  purified,  but  the  operation  is  not  prof¬ 
itable.  That  is  to  say,  sewage  farming  cannot,  save  in  ex¬ 
ceptional  instances,  be  made  to  pay.”  Mr.  Brundell  also 
brings  up  the  additional  factor  of  cold  winter  weather  and 
seriously  doubts  whether  or  not  the  system  could  be  suc¬ 
cessfully  used  in  cold  countries  on  account  of  the  protracted 
cold  winter.  A  very  good  short  account  of  the  Berlin,  Ger¬ 
many,  sewage  farm  is  given  by  Barwise. 

Chemical  precipitation  was  an  effort  made  on  the  part 
of  some  to  entirely  purify  sewage  by  the  addition  of  chemi¬ 
cals.  The  principal  precipitants  used  are  lime,  iron,  alumi¬ 
num  hydrate,  alum,  and  copperas.  Although  the 
chemicals  used  for  this  purpose  are  almost  innumerable, 
results  tend  to  show  that  only  the  solid  matter  in  suspen¬ 
sion  is  removed,  while  the  sewage  is  deodorized  for  the 
time  being.  Extensive  experiments  with  chemical  pre¬ 
cipitation  of  sewage  were  made  by  Mr.  Bibden  in  England 
as  well  as  by  the  Massachusetts  State  Board  of  Health  in 
America  under  the  supervision  and  charge  of  Allen  Hazen. 
The  cost  of  constructing  a  plant  for  the  chemical  precipi- 


I 


—  6  — 

tation  of  sewage  is  considerable,  besides  there  is  left  on 
hand  a  sludge  which  must  be  disposed  of.  This  would  not 
be  a  serious  drawback  if  it  were  valuable  as  a  fertilizer, 
but  chemical  analysis  seem  to  show  the  contrary  to  be 
true.  On  the  whole,  chemical  precipitation  is  not  re¬ 
garded  with  favor  by  the  majority  of  experts. 

Filtration  is  the  'application  of  raw  or  precipitated 
sewage  to  beds  composed  of  various  substances,  either 
continuously  or  intermittently.  In  1870  the  first  report  of 
the  royal  commission  on  the  best  means  of  preventing  the 
pollution  of  rivers  was  made.  In  regard  to  the  filtration 
method  it  contained  the  following: 

“The  process  of  filtration  through  sand,  chalk,  or  cer¬ 
tain  kinds  of  soil,  if  properly  carried  out,  is  the  most 
effective  means  for  the  purification  of  sewage.  In  con¬ 
tinuous  filtration  the  sewage  is  applied  to  the  beds  indef¬ 
initely  without  giving  them  time  to  rest.  This  was  found 
to  be  unsuccessful  so  a  system  of  allowing  the  beds  to  rest 
at  stated  periods  was  tried  and  found  to  be  highly  success¬ 
ful.  This  latter  method  is  known  as  the  intermittent  fil¬ 
tration  of  sewage.  This  system  of  filtration  recognizes 
the  fact  that  the  active  agents  in  the  purification  of 
sewage  are  minute  plants;  variously  named  microbes,  mi¬ 
cro-organisms,  germs,  bacteria,  etc.  Bacteria  is  the  name 
now  commonly  accepted  and  used  in  scientific  writings  and 
discussions. 

Certain  species  of  bacteria  have  the  power  of  breaking 
up  the  complex  organic  compound  of  sewage  into  simpler 
inorganic  harmless  compounds.  This  process  is  commonly 
spoken  of  as  nitrification  and  the  bacteria  as  nitrifying 
organisms,  because  the  chief  inorganic  substances  formed 
them  are  nitrites  and  nitrates.  There  are  other  species  of 
bacteria  however  that  decompose  organic  materials  into 
various  gases,  hydrogen  (H),  carbon  dioxide  (C02),  marsh 
gas  (CH4),  nitrogen  (N),  ammonia  (NH3),etc.  Gas-produc¬ 
ing  bacteria  will  be  spoken  of  again  in  connection  with 
the  septic  tank. 

Filter  beds,  as  those  used  for  filtration  of  sewage  are 
called,  are  composed  o*f  various  materials:  sand,  gravel, 


-7  — 


coke  breeze,  chalk,  clinkers,  clay,  cinders,  ballast,  etc 
Experiments  with  different  materials  have  been  tried  at 
various  places.  The  Massachusetts  State  Board  of  Health 
has  probably  done  the  most  work  along  this  line  in 
.  America. 

Dibden  and  Thudicum  of  England,  however,  are  the 
pioneers  in  this  line  of  investigation.  There  is  no  small 
amount  of  discussion  as  to  the  relative  merits  of  the  vari¬ 
ous  substances  used  as  fillers  in  filter  beds.  But  no  matter 
what  the  material,  the  object  to  be  obtained  in  all  cases  is 
the  same,  namely,  a  substance  that  will  serve  as  a  resting 
place  for  the  gelatinous  masses  of  bacteria.  Any  substance 
that  will  do  this  and  still  be  porous  enough  to  admit  of 
complete  aeration  may  be  termed  a  successful  filler. 

For  plans  of  beds,  materials  used,  dimensions,  etc.,  no 
better  information  can  be  obtained  than  that  in  the  Mas¬ 
sachusetts  State  Board  of  Health  reports,  and  for  the  plans 
and  specifications  of  the  Iowa  State  College  Sewage  Plant 
by  Prof.  Marston  (19). 

There  remains  yet  the  septic  tank.  It  is  a  tank  in  which 
the  sewage  is  retained  for  a  limited  time  in  order  to  allow 
the  anaerobic  bacteria  to  work.  Two  kinds  have  been 
employed,  the  open  and  the  closed.  Most  experimenters 
along  these  lines  are  now  of  the  opinion  that  one  is  as 
effective  as  the  other,  on  account  of  the  scum  (composed 
essentially  of  bacteria)  that  covers  the  sewage  in  the  tank. 
According  to  L.  P.  Kinnicutt  (16)  the  following  changes  are 
due  to  anaerobic  bacteria  in  a  septic  tank.  First,  the  decom¬ 
position  of  cellulose  and  allied  substances,  and  the  formation 
of  marsh  gas.  Second,  the  decomposition  of  complex 
nitrogenous  organic  matter,  with  the  production  of  am¬ 
monia,  hydrogen  and  odoriferous  substances.  Third,  the 
removal  of  oxygen  from  nitrates  with  simultaneous  oxida¬ 
tion  of  organic  matter. 

As  has  been  stated  before,  the  filter  bed  gives  an  excel¬ 
lent  opportunity  for  the  action  of  aerobic  bacteria,  to 
which,  according  to  Kinnicutt,  the  following  changes  are 
due:  The  conversion  of  urea,  and  similar  substances  into 
ammonium  salts,  and  the  conversion  of  ammonium  salts 


—  8  — 


into  nitrates.  This  being  the  case  the  question  at  once 
arises,  why  would  not  the  system  of  intermittent  filtration 
and  of  the  septic  tank  work  well  together.  Experience  has 
taught  that  they  do  and  it  is  to  a 'system  of  this  kind  that 
the  remainder  of  this  paper  will  be  devoted,  taking  as  a. 
basis  the  sewage  system  of  the  Iowa  State  College.  Great 
credit  is  due  Prof.  Marston,  who  introduced  this  system  in 
Iowa. 

TABULATED  BACTERIOLOGICAL  RESULTS. 


TEMPERATURE. 


September  i.. 
September  2.. 
September  3.. 
September  4. 
September  5.. 
September  5.. 
September  5.. 
September  6.. 
September  7.. 
September  8.. 
September  9.. 
September  10.. 
September  n . . 
September  12. . 
September  12.. 
September  12.. 
September  13. . 
September  14.. 
September  15 . . 
September  16.. 
September  17. . 
September  18. . 
September  19. . 
Septemper  19. . 
September  19. . 
September  20.. 
September  21 . . 
September  22.. 
September  23. . 
September  24.. 
September  2 5.. 
September  26.. 
September  27 . . 
September  27.. 
September  27. . 
September  28. . 
September  29.. 
September  30. . 

Orfnhpr  t 

W.  E . 

2, 400 
4, 800 
880 
1,320 
600 

E.  E  . 

W.  E . 

E.  E . 

YV.  E . . . 

9,000,000 

Tank . 

1,800.000 

E.  E  . 

1,920 

1,840 

1,  560 

1, 420 
3.800 
3,640 
2, 160 

W.  E . 

W.  E  .. 

E.  E . 

W.  E  . 

W.  E . 

E.  E 

Manhole . 

8,600  00c 

Tank  .. 

2,050.000 

E.  E 

2,400 
3.600 
2, 760 
3,96o 
3,78o 
2,920’ 
4,080 

W.  E 

E.  E  .. 

W.  E... 

W,  E 

W.  E  .. 

W  E  . . 

M  anhnlfi 

7,260,000 

Tank 

2, 170.(00 

W  E 

3, 660 
2,  520 
2, 760 
5,400 
9,000 
9, 120 
8,040 
8, 160 

YV  E  . 

W  E 

W  E 

W  E 

W  E 

W  E  . 

E  E 

M  anhnlp 

9,600,000 

Tank 

6, 960, 000 

E  E 

4,400 
4, 100 
3, 800 
3,76o 
3, 720 

3,720 

E  E 

E  E  . . 

OO 

OO 

LT» 

O 

8 

3,245,000 

3, 660 

E  E 

(Trfnhpr  o 

E  E 

Orfnhpf  ^ 

E  E 

Orfnhpr  3 

M  anhnlp 

4,800,000 

Oct^her  3 

T  ank 

4, 200, 000 

Orfnhpr  | 

E  E 

5, 160 
4,820 
5,040 
5,880 

5,4oo 
6, 120 
7.280 

Orfnhpr  ^ 

E  E 

Orfnhpr  h 

W  E 

O^fnhpf  7 

W  E 

Orfnbpf  & 

W  E 

Opfnhpf  Q 

E  E 

Ocfohpr  in 

YV  E 

( )pf n h^r  t n 

Manhnlp 

6, 480, 000 

Opfnhpf  in 

l^nk 

4,618,000 

October  T  T 

E  E 

4, 200 
4,080 

October  12 . 

E.  E  . 

BACTERIOLOGICAL  RESULTS  — Continued. 


D.ATE. 

From. 

TEMPERATURE. 

Manhole. 

Tank. 

c 

<u 

SE 

1  w 

< 

•V 

a 

£ 

E.  E  . 

3,600 
5,76o 
4.020 
4.  36o 
3,720 

E.  E . 

E.  E . 

E.  E . 

F.  E . 

4, 724,000 

5,  650. 000 

October  18 . 

E.  E . 

4.700 

•2.640 

E.  E . 

W.  E . 

4.  200. 
3-  700 
3,820 

W.  E . 

W  E . 

6, 760, 000 

October  24  .... 

Tank . 

5,040,000 

W.  E . 

4.6:0 
3,240 
3,720 
3-  58o 
2,040 

1 ,  '320 

2,  880 

E.  E . 

W.  E . 

W.  E . 

1 . 

E.  E . 

E.  E . 

W.  E . 

October  31. ... 

7,  560, 000 

Tank . 

5,  200,  000 
4,941,000 

4,230 

November  1.. 
November  2.. 
November  3.. 
November  4.. 
November  5.. 
November  6.. 
November  7.. 
November  7.. 
November  7.. 
November  8.. 
November  9.. 
November  10.. 
November  n.. 
November  12.. 
November  13.. 
November  14.. 
November  14.. 
November  14.. 
November  15.. 
November  16.. 
November  17.. 
November  18 
November  19.. 
November  20.. 
November  21  . 
November  22. 

November  23.. 

November  2\. . 
November  24 
November  24.. 
November  25. . 
November  26. . 
November  27.. 
November  28.. 
November 29. . . 
November  30. . 
December  1. 
December  2... 
December  3... 
December  4.. 
December  5. .. 
December  6... 
December  7... 
December  8... 
December  9... 
December  10. . . 

E.  E . 

6, 064, 800 

3.  600 
3.720 

2,  280 
2,280 
2,  4CO 
2.  640 
2,  040 

W.  E . 

E.  E . 

W.  E . 

W.  E . 

;  . 

W.  E . 

1 

W.  E . 

Manhole . 

6,  800, 000 

lank . 

4, 350, 000 

W.  E . 

2.520 

3-  180 
3.560 
2,520 
4.360 
4,  120 

4- 500 

W.  E . 

E.  E . 

E.  E . 

i . 

E.  E . 

W.  E . 

W.  E . 

Manhole . 

5, 796.  000 

Tank . 

3,  432,  oco 

E.  E . 

2.720 
2.  560 

3,520 

2,760 
3.080 
3.240 
2,  280 

I,  800 

No  de- 
velm’t 
2,060 

E.  E . 

E.  E . 

W.  E . 

W.  E . 

E.  E . 

E.  E . 

E.  E . 

E.  E  . 

. .  J 

E.  E . 

l 

Manhole . 

1,016,000 

Tank . 

1,260, 000 

E.  E . 

1,  620 

No  effluent. 

E.  E . 

4, 200 

No  effluent  . 
No  effluent. . . 

E.  E . 

4.537,333 

.  . 

3, 014, 000 

3,000 

2.  26l 

No  effluent  .. 

E.  E . 

3  6*o 
920 

1  640 

1, 840 
3,88o 
280 

E.  E . 

E.  E . 

E.  E . 

E.  E . 

E  E . 

Effl’nt  frozen 
Effl’nt  frozen 
E.  E . 

4, 000 

-  10 


BACTERIOLOGICAL  RESULTS— Continued. 


DATE. 

a 

0 

£ 

TEMPERATURE. 

Manhole. 

1 

Tank. 

Effluent. 

< 

<D 

C3 

£ 

December  n. . . 
December  u. .. 
December  n. . . 
December  12. .. 
December  13. .. 
December  14. . . 
December  15. . . 
December  16. . . 
December  17-. . 
December  18. . . 
Decemberi8... 
December  18. . . 
December  19. . . 
December  20. . . 
December  21. .. 
December  22. .. 
December  23. .. 
December  24. .. 
December25. . . 
December  25... 
December  25. .. 
December  26. . . 
December  27. .. 
December  28. . . 
December  29. .. 
December  30. . . 
December  31. . . 
1900. 

January  t 

E.  E . 

1.080 

Manhole . 

92, 000 

Tank . 

288, 000 

Effl’nt  frozen 
W.  E . 

2, 120 
7.800 
2,920 
2, 160 

s. 

W.  E . 

W.  E . 

W.  E . 

W,  E . 

W.  E . 

Manhole . 

1,087,000 

Tank . 

1. 248, 000 

W.  E . 

2,  520 
2,800 
680 
3,440 
3,720 
3,240 
2,960 

W.  E . 

W.  E . 

W.  E . 

W.  E . 

W.  E . 

W.  E . 

Manhole . 

1,270,000 

Tank . 

1,008,000 

W.  E . 

3,  20 
2,740 
2,  560 
2,  120 
1,200 
600 

720 

W.  E . 

W.  E . 

W.  E . 

W.  E . 

W.  E . 

8i6,333 

848; 000 

2,319 

W.  E . 

lanuary  1 . 

Manhole . 

848, 000 

lanuary  t  k 

Tank . 

726, 000 

lanuary  2 . 

W.  E . 

800 

920 

1,000 

7,272 

J  anuary  3 . 

W.  E  . 

I anuary  4 . 

W.  E . 

848,000 
363,  7oo 

726,  000 

830 

February  i.... 
February  i.... 
February  i. .  . . 
February  2. . . . 
February  3.... 
February  9.  .. 
February  9. . . . 
February  15.. . . 
February  15.. .. 
February  22. . .. 
February  22  . . . 
February  25  .  . . 
February  25  . .. 
February  29  . . . 
February  29  . . . 

March  6  . . . 

W.  E . 

Manhole . 

287, 900 

Tank . 

W.  E . 

x  .800 
1. 280 

W.  E . 

3  451 

Manhole . 

651, 200 

Tank . 

509,000 

Manhole . 

20, 600 

Tank . 

12.240 

M  anhole .... 

468, 700 

Tank . 

419, 200 

Manhole.  . . . 

132, 400 

Tank 

108. 000 

M  anhole _ 

No  devel. 

Tank 

66,  520 
233,8io 

3  45i 

Manhole . 

' 

345, 533 
80, 600 

March  6 

Tank  .... 

No  devel. 

March  to  .  .  . 

Manhole . 

184, 600 

M arch  m  .  . 

T  ank 

98, 700 

March  11 

W.  E 

23,400 

39,000 

21,000 

12,000 

M  arch  12 

W.  E.... 

March  T3  .  .  . 

W.  E . 

March  14 

W.  E . 

jVlarch  14 

Manhole .  ... 

204, 500 

March  14 

Tank 

126, 300 

March 

W.  E  . 

36,000 

March  t 8 

M  anhole . 

58, 800 
132, 125 

26, 480 

April  i 

W  E 

112,  500 

l6,  800 

15, 000 
15,600 
12, 600 
6,000 

13,  400 

14,  400 
13, 200 
21,000 
24, 000 

April  2 

W.  E  . 

April  3 

W.  E . 

April  4 

W.  E . 

April 

W  E 

4  pr'  l  6 

W  E 

April  7 

W  E 

April  8 

W  E 

Anril  q 

WE.. 

7 . 

Anril  10 . 

W.  E.. . 

BACTERIOLOGICAL  RESULTS  -  Continued. 


DATE. 

From. 

TEMPERATURE. 

Manhole. 

Tank. 

Effluent. 

J— " 

<5 

0) 

01 

£ 

W.  E . 

17,0:0 
15, 600 

W.  E . 

3,151.200 

x.999, 800 

W.  E . 

24,  000 
16, 800 
18, 6:0 
19. 200 
18,000 
17, 5oo 
7,200 
4, 800 
30, 000 
14,400 
12,000 
6,-000 
5. 400 

W.  E . 

W.  E . 

W.  E... 

W.  E . 

W.  E . 

E.  E . 

E.  E . 

E.  E . 

E.  E  . 

April  23 . 

E.  E . 

W.  E... 

April  2i  .... 

E.  E  . 

April  25 . 

Manhole  .... 

1,090,800 

787, 800 

W.  E.  . 

6i  degrees 
64  degrees 
63  degrees 
59  degrees 
63  degrees 

63  degrees 

64  degrees 

7. 200 
j  8  0 
0, 600 

4. 200 
5,400 

3, 600 
4,200 

W.  E  .. 

W.  E . 

W.  E... 

W.  E . 

13, 260 

W.  E . 

2, 121,000 

1,392,800 

Mav  2  .... 

W.  E . 

May  2  . 

Manhole  .... 

666, 600 

May  2 . 

Tank . 

242, 000 

Mav  3 . 

W.  E . 

62  degrees 

60  degrees 

63  degrees 

61  degrees 
61  degress 
61  degrees 

61  degrees 
63  degrees 

62  degrees 

63  degrees 

63  degrees 
68  degrees 
68  degrees 

64  degrees 

65  degrees 
63  degrees 

60  degrees 

61  degrees 

62  degrees 

63  degrees 

1,  500 
10, 200 

3.000 
2, 400 
1,800 
3, 600 

2,  400 
210 

2, 400 
1,940 

2,0C0 

4.  '6o 
4,  200 

3. 600 
3.000 

9. 600 
2,700 
2, 100 

1 .'  500 
1,  200 

Mav  4 . 

W.  E . 

May  c, . 

W.E . 

Mav  6 . 

W.E . 

73  degrees 
72  degrees 

69  degrees 

71  degrees 
76  degrees 

70  degrees 

72  degrees 

71  degrees 

73  degrees 
56  degrees 
69  degrees 
62  degrees 
50  degrees 
67  degrees 

72  degrees 
78  degrees 
78  degrees 

May  7 . 

W.E . 

Mav  8 . 

E.E . 

Mav  9 . 

E.  E . 

Mav  10 . 

E.E  . 

Mav  11 . 

W.E . 

Mav  12 . 

W.E . 

Mav  13 . 

'  W.E . 

Mav  14 . 

W.E . 

Mav  15 . 

W.E . ‘ 

Mav  16 . 

E.E . 

May  17 . 

W.E  . 

Mav  18 . 

W.E . 

Mav  19 . 

W.E . 

Mav  20 . 

W.E . 

May  21 . 

May  22 . 

E.E . 

W.E . 

Mav  22 . 

Manhole  .... 

900, 000 

Mav  22 . 

Tank  . 

1, 800,000 

Mav  23 . 

W.E . 

76  degrees 
73  degrees 

77  degrees 

81  degrees 

82  degrees 
76  degrees 

79  degrees 

80  degrees 

81  degrees 

63  degrees 

63  degrees 

64  degrees 

65  degrees 

67  degrees 

68  degrees 
68  degrees 

68  degrees 

69  degrees 

2,  too 

1.800 
2,40 

4, 200 
3.000 
3,600 
2,  400 

2.800 

1. 800 

Mav  24 . 

W.E . 

Mav  25 . 

W.E . 

Mav  26 . 

W.E . 

May  27 . 

W.E . 

May  28 . 

W.E . 

Mav  29 . 

W.E . 

Mav  30 . 

W.E . 

Mav  31 . 

W.E  . 

2,077 

1 , 021 , 000 

783, 3oo 

June  1 . 

E.E . 

82  degrees 

81  degrees 
80  degrees 
73  degrees 

82  degrees 

69  degrees 
69  degrees 
69  degrees 
69  degrees 
69  degrees 

6  3 

June  2 . 

E.E . 

1 ,  200 
900 
1,800 
5.400 

June  3 . 

E.E . 

June  4 . 

W.E . 

June  5 . 

W.E . 

June  5 . 

Manhole . 

x, 272,600 

June  S . 

Tank . 

1. 636, 200 

J  une  6 . . . . 

W.E . 

W.E . 

81  degrees 
80  degrees 
79  degrees 
78  degrees 
85  degrees 

69  degrees 
69  degrees 
69  degrees 
69  degrees 
69  degrees 

150 
2,  100 
I,  800 

3,ooo 

90 

June  7 . 

June  8 . 

W.E . 

lime  q . 

W.E . 

June  10 . 1  E.  E . 

—  12  — 


BACTERIOLOGICAL  RESULTS  — Continued. 


June  ii. 
June  12. 
June  13. 

Iune  14. 
une  15. 
une  15. 
une  15. 
une  16. 
June  17. 
June  18. 
June  19. 
June  19. 

June  19. 
une  20. 
une  21 . 
June  22. 
June  23. 
June  24. 
June  25. 
June  2a 
June  26. 
June  26. 
June  27. 
June  28. 
June  29. 
June  30. 

j®  ■' 

July 
July 
July 
July 
July 
July 
J  uly 
J  uly 
July 
uly 
uly 
ulv 
uly 
uly 
uly 
uly 
uly 
uly 
uly 
uly 
uly 
July 
uly 
uly 
uly 
July 
Ju  y 
July 
July 
uly 
uly 
uly 
uly  23 
July  24 
July  25 
July  26 
July  27 
July  28 
July  29 
July  3° 
July  31 
August 
August 


E.E . 

W.E.  . . . 

E.E . 

W.E . 

E.E . 

Manhole . 

Tank  . 

E.E  . 

W.E . 

W.E  . 

W.E . 

Manhole . 

Tank . 

W.E  . 

E.E . 

E.E . 

W.E . 

E.E . 

E.E . 

W.E . 

Manhole . 

Tank  .... 

E.E . 

W.E . 

E.E . 

E.E . 

W.E . 

W.E . 

W.E . 

W.E . 

Outlet  flooded 
Outlet  flooded 

W.E . 

W.E . 

E  E . 

Outlet  flooded 
Outlet  flooded 

W.E . 

Manhole..  .. 
Manhole  ..  .. 
Manhole  ..  .. 
Tank . 


Tank . 

Tank  . 

Tank . 

W.E . 

E.E . 

E.E . 

W.E . «. 

W.E . 

E.E  . 

M  anhole . 

Tank  , .  . 


E.E . 

E.  E . 

E.E . 

E.jr . 

*  Effluent 

E.E . 

Manhole  . . 
Tank  . 

*  Effluent 

*  Effluent 

*  Effluent . 

E.E . 

W.E . 

E.E . 

W.E . 

W.E . 

E.E . 

Manhole  ..  .. 


TEMPERATURE. 


51  degrees 
70  degrees 
74  degrees 
83  degrees 
79  degrees 


78  degrees 
75  degrees 
73  degrees 
82  degrees 


80  degrees 
76  degrees 
74  degrees 
73  degrees 
73  degrees 
86  degrers 
89  degrees 


76  degrees 
81  degrees 
76  degrees 
64  degrees 
70  degrees 
85  degrees 
92  degrees 
90  degrees 


84  degrees 
77  degrees 
82  degrees 


72  degrees 


72  degrees 
78  degrees 
82  degrees 
84  degrees 
69  degrees 
72  degrees 


78  degrees 
68  degrees 
73  degrees 
72  degrees 

82  degrees 


78  degrees 

75  degrees 
78  degrees 
90  degrees 
80  degrees 

76  degrees 


09  degrees 
69  degrees 
67  degrees 
69  degrees 
69  degrees 


99  degrees 
68  degrees 

68  degrees 

69  degrees 


69  degrees 
69  degrees 
69  degrees 
69  degrees 

69  degrees 

70  degrees 
72  degrees 
77  degrees 
67  degrees 
72  de  rees 
72  degrees 
72  degrees 
72  degrees 
72  degrees 
70  degrees 
69  degrees 
72  degrees 


76  degrees 

75  degrees 

76  degrees 


72  degrees 
68  degrees 
68  deg  ees 
68  degrees 
62  degrees 

62  degrees 
62  degrees 
72  degrees 
72  degrees 
72  degrees 
74  degrees 
72  degrees 
72  degrees 
67  degrees 

67  degrees 
72  degrees 
72  degrees 
71  degrees 
71  degrees 

71  degrees 

68  degrees 
66  degrees 


70  degrees 
72  degrees 

72  degrees 

73  degrees 
73  degrees 

71  degrees 
71  degrees 


.545,400 


[,363,600 


[ ,  050.  800 


I,  318, 100 


363, 600 
104,030 
242, 40© 

(Agarf) . . . 
(Agar)  ' 
(Agarf)  .. 
(Agarf)  .. 


7,  575,ooo 


(Too  ff) 


3,908,700 
1 , 346,  600 


1, 324,000 


, 090, 000 


1,515, 000 


1,391,300 


(Ge’atine) 
(Agarf).  . 
(Agar) 
(Gelatine) 
426  000 
342,  400 


090,000 


302,600 


15,  800 
4,000 
3,000 
6,000 
2.400 


2,400 
1,600 
3,000 
4, 100 


3.600 
2,400 
450 
560 
640 
1,  200 
1,410 


570 
160 
540 
850 
780 
840 
980 
1.  040 


[5.  coo 
540 
I,, 600 


2.400 


114,130 

250 

900 

370 

6.000 

130 

8, 040 


360 

4.800 

4,200 

9,600 

t.  600 


210 
.260 
90 
.  800 
360 
980 


2,359 


2, 270 


*  Effluent  under  water,  f  Agar  for  gas.  ff  Too  thick  to  count. 


—  13- 


BACTERIOLOGICAL  RESULTS  — Continued. 


DATE. 

From. 

TEMPERATURE. 

Manhole. 

Tank. 

Effluent. 

< 

0) 

£ 

Tank  . 

64  degrees 
74  degrees 
71  degrees 

74  degrees 
7^  degrees 

75  degrees 

76  degrees 
71  degrees 
68  degrees 
76  degrees 

75  degrees 

76  degrees 
76  degrees 

672,000 

1,200 

100 

3,600 

7o 

60 

400 

W.E . 

77  degrees 
81  degrees 

78  degrees 
88  degrees 

84  degrees 

85  degrees 

F.  E. 

W.E . 

August  5 . 

E.E . 

W.E . 

W.E . 

87,870 

80,800 

August  8 . 

E.E . 

82  degrees 

83  degrees 
88  degrees 
87  degrees 

300 

400 

20 

120 

August  9  . .  . 

E.E . 

W.E . 

August  10 . 

August  T  T  . 

E.E . 

August  12 . 

*Effluent  .... 

August  13 . 

^Effluent  .... 

August  14 . 

*Effluent  .... 

August  15 . 

*Effluent  .... 

August  16 . 

*Effluent  .... 

August  17 . 

W.E . 

92  degrees 

76  degrees 
70  degrees 
68  degrees 

90 

August  17 

Manhole.  . 

68,000 

August  17 . 

Tank . 

26, 000 

August  18 . 

*Effluent  .... 

August  19 
August  20 . 

.... 

*Effluent  .... 

August  21 . 

W.E . 

80  degrees 
79  degrees 

75  degrees 
75  degrees 

320 

430 

August  22 . 

E.E . 

Angust  22 . . . 

Manhole 

120, 000 

August  22 . 

Tank . 

84,00? 

August  2} . 

W.E . 

85  degrees 

86  degrees 
84  degrees 

80  degrees 

81  degrees 
80  degrees 
88  degrees 
83  degrees 

82  degrees 

76  degrees 
76  degrees 
75  degrees 
73  degrees 
73  degrees 
72  degrees 

72  degrees 

73  degrees 
73  degrees 

q8o 

380 

123 

l6o 

290 

3X0 

680 

640 

360 

August  24 . 

E.E . 

August  25 . 

E.E. . 

E.E . 

August  26 . 

August  27  ... 

August  28 . 

E.E . 

W.E . 

August  29 . 

W.E . 

August  30 . 

E.E  .. 

August  31 . 

W.E . 

403, I18 

215,  700 

560 

*  Effluent  under  water. 


Average  number  of  germs  per  cubic  centimeter,  in  effluent. 


MONTH .  1899. 

August . 

September . 

October . 

November . 

December . 

1900. 

January . 

February . 

March... . 

April . 

May .  . 

June . 

July . 

'  August . 

September . , . 


AVERAGE. 

2,  246 
3,660 
4, 230 
2,261 

2,319 


830 

3,451 

2 ',480 

13, 263 
3,077 

2,  359 
2,270 

546 

850 


—  14  — 


A  verage  number  of  bacteria  per  c.c.  in  manhole  and  tank. 


MONTH 

Manhole. 

Tank. 

August,  1899 . 

2. 392,600 
8,815,000 
6,064,800 
4,537,333 
8j6,333 
848,000 
345,  533 
132, 125 

2, 121,000 
1,021,000 
I,3l8,IOO 
3,908,700 
403,118 
I,l8l.533 

1.358.300 
3, 245, 000 
4,941,000 
3,014,000 

848, poo 
726. 000 
233,810 
1 12, 500 
1,392,800 
783,  300 

1.391.300 
4,  578, 333 

215.700 

383,733 

September,  1899 . 

October,  1899  . . 

November,  1890 . . . 

December,  1809 . 

January,  1900 . 

February,  1900 . 

March,  1900  .  . 

April  1900 . . 

Mav  1900  . . 

1 11  n  e  190^ . . . . 

July.  T900 . . 

August,  1900 . 

September,  1900 . 

BACTERIOLOGICAL  ANALYSIS  OF  THE  COLLEGE  SEWAGE  FROM 

SEPT.  1,  1899,  TO  SEPT.  1,  1900. 

The  college  sewage  system  is  a  combination  of  several 
systems  combined  into  one.  It  combines  the  system  of 
the  septic  tank  with  that  of  intermittent  filtration.  For  a 
very  excellent  and  (20)  detailed  description,  see  the  article 
in  Centralblatt  No.  15,  on  the  Iowa  State  College  Sewage 
D'sposal  Plant,  by  Drs.  Pammel,  Weems,  and  Professor 
Marston,  and  Contribution  No.  1  of  the  Iowa  State  Col¬ 
lege  (19). 

Bacteriological  analysis  have  been  made  of  the  effluent 
each  day,  while  once  each  week  samples  have  been 
taken  from  the  manhole  and  the  tank,  as  well  as  the  efflu¬ 
ent,  of  which  both  bacterological  and  chemical  analyses 
have  been  made.  The  chemical  analyses  have  been  under 
the  direction  of  Dr.  Weems,  who  has  from  time  to  time 
published  some  very  interesting  results,  but  as  it  is  my 
intention  to  deal  with  the  bacteriological  side  only,  no 
chemical  results  will  be  given^  only  as  they  may  serve  to 
elucidate  some  point  in  connection  with  the  bacteriological 
analyses. 

In  making  the  cultures,  petri  dishes  of  a  standard  size 
have  been  used.  The  dilution  method  has  been  employed 
with  the  manhole  and  tank  samples,  it  having  been  found 
on  trial  that  without  dilution  it  was  practically  impossible 


—  15  — 


to  count  the  number  of  colonies.  For  this  dilution  one- 
tenth  of  a  cubic  centimeter  of  sewage  is  put  into  ten  cubic 
centimeters  of  sterilized  water,  and  one-tenth  c.c.  of  this 
taken  to  make  the  culture.  With  the  effluent  no  dilution 
has  been  made.  Two  methods  of  counting  the  plates  have 
been  employed.  One  is  to  divide  the  plates  by  means  of  a 
dividing  circle  into  twTenty  equal  divisions,  counting  three 
of  these  divisions,  dividing  by  three  to  strike  an  average, 
and  multiplying  by  twenty  the  number  of  divisions  on  the 
plate,  and  by  ten,  the  denominator  of  the  fractional  part 
of  a  c.c.  of  sewage  taken  to  make  the  culture.  Of  course, 
when  dilutions  were  made  the  above  result  was  multiplied 
by  the  denominator  of  the  fractional  part  of  a  c.c.  used,  as 
to  illustrate,  21+18+12-51—3—17X20—340X10  3,400X 
101—843,400.  The  above  sample  being  diluted  by  ten  c.c. 
of  sterilized  water  to  1-10  of  a  c.c.  of  sewage. 

The  other  method  is  practically  the  same.  The  plate  is 
divided  into  sixty  square  centimeters;  three  square  centi¬ 
meters  are  averaged  and  multiplied  by  the  number  of 
square  c.c.  in  the  plate  and  the  fraction  of  the  denominator 
of  the  dilution. 

In  each  method  care  was  taken  to  obtain  a  good  average 
of  the  plate.  As  an  illustration,  if  there  was  a  spot  where 
the  colonies  were  especially  thick  or  thin,  counts  were 
taken  from  them,  and  also  from  a  spot  containing  about  an 
average  number  of  bacteria,  if  possible. 

The  pipettes,  petri  dishes,  etc.,  used  in  the  wTork,  were 
sterilized  by  dry  heat  for  one  hour  and  kept  away  from 
dust  and  moisture. 

The  media  used  in  these  experiments  has  been,  in  the 
main,  ordinary  agar  agar,  gelatine  having  been  used  on  sev¬ 
eral  occasions  to  determine  the  variations  between  the 
number  of  colonies  produced  by  agar  and  gelatine  cultures 
respectively.  It  was  found  that  on  gelatine  plates  there  is 
usually  a  slight  increase  in  the  number  of  colonies,  but  on 
account  of  the  liquefying  properties,  it  has  not  given  as 
much  satisfaction  as  agar  cultures. 

Another  method  employed  for  the  determination  of  gas 
producers  is  of  special  interest,  as  it  can  be  shown  by 


—  16  — 


making  parallel  cultures  the  relative  number  of  gas  pro¬ 
ducers  present  in  a  c.c.  of  sewage. 

A  method  which  has  given  excellent  results  is  as  fol¬ 
lows:  Take  a  tube  of  ordinary  agar,  melt  and  pour  in  a 
petri  dish,  after  it  has  cooled  to  such  a  degree  that  it  is 
just  liquid,  add  one-tenth  cc.  of  sewage  and  immediately 
turn  it  around  rapidly  in  order  to  secure  equal  distribu¬ 
tion  of  the  sewage;  then,  after  it  has  been  cooled  so  far  as 
to  become  solid,  add  another  tube  of  melted  agar,  care 
being  taken  that  it  is  not  too  hot,  after  which,  without 
stirring,  set  it  away  to  develop.  This  last  agar  forms  a 
layer  containing  no  germs,  if  the  work  has  been  properly 
done.  The  anaerobic  gas  producers  working  in  the  lower 
portion  produce  gas,  which  appears  in  the  agar  as  minute 
air  bubbles. 

The  effluent  of  July  12,  1900,  after  standing  one  week, 
showed  25  gas  producers  in  the  plate,  and  as  one-tenth 
c.c.  of  sewage  from  the  effluent  was  used  in  making  the 
culture,  there  would  be  250  gas  producers  to  the  c.c.  of 
effluent.  The  number  of  germs  counted  from  a  parallel 
culture  was  2,400,  which  means  that  approximately  ten 
per  cent  of  the  total  number  of  germs  were  gas  producers, 
the  above  result  being  obtained  from  the  sample  of  efflu¬ 
ent  taken  from  the  west  bed.  The  temperature  of  the  air 
and  sewage  being  72°  Fahrenheit.-  A  similar  culture  from 
the  tank  on  the  same  date  showed  1  IB  gas  producers  in  the 
plate,  making  114,  180  gas  producers  to  the  c.c.  of  sewage, 
or  about  33^  per  cent  of  the  germs  in  the  tank  at  that  time 
were  gas  producers,  the  temperature  of  the  sewage  in  the 
tank  being  62°.  The  total  number  of  germs  for  the  c.c. 
being  342,400. 

The  manhole  sample  taken  July  12th  and  examined  July 
17th,  shows  a  still  greater  percentage,  there  being  104,030 
gas  producers  to  the  c.c.,  or  43  per  cent  of  the  germs  in  the 
raw  sewage  at  that  time  were  gas  producers.  The  tem¬ 
perature  of  the  raw  sewage  was  68°,  the  total  number  of 
germs  to  the  c.c.  on  an  ,ager  culture  being  242,400.  Other 
ctiltures  were  made  in  the  same  manner,  with  approxi¬ 
mately  the  same  results. 


- 17- 


It  will  be  noticed  that  the  percentage  of  gas  producers 
is  highest  in  the  manhole,  and  lowest  in  the  effluent, 
while  the  number  in  the  tank  lies  between,  which  would 
seem  to  show  that  the  gas  producers  are  destroyed  while 
the  sewage  is  passing  through  the  tank  and  filter  bed, 
which  is  very  desiraable,  in  view  of  the  fact  that  gas  pro¬ 
ducing  species,  while  not  actually  condemned  as  patho¬ 
genic,  are  to  be  regarded  with  suspicion. 

The  primary  object  of  bacteriological  analysis  of  sew¬ 
age  is  to  determine  the  number  of  germs  present  per  c.c. 
in  the  sewage  at  the  different  stages  of  its  purification. 
By  such  data  the  efficiency  of  the  beds  and  other  parts  of 
the  system  may  be  readily  determined. 

The  number  of  germs  present  per  c.c.  determine  the 
relative  purity  of  the  water,  but  far  more  important  from 
a  sanitary  standpoint,  is  the  kind  of  germs  present. 

But  little  attention  has  been  given  to  the  determination 
of  species,  except  incidentally.  Bacillus  cloacea ,  B.  coli- 
communis ,  and  some  others  were  determined  by  Dr.  Pam- 
mel  and  0.  J.  Fay,  while  I  have  run  out  B.  prodigiosus , 
B.  mutabalis,  and  several  other  species. 

Bacillus  prodigiosus  does  not  occur  in  the  sewage  to  any 
considerable  extent,  it  having  been  found  up  to  date  only 
three  times;  once  in  the  tank  on  June  19th,  and  twice  in 
the  effluent,  once  on  the  22nd  of  June  in  the  east  effluent, 
and  once  on  the  27th  of  June  in  the  west  effluent.  At 
no  time  was  more  than  one  colony  found  on  the  plates 
in  any  of  the  above  cultures.  Its  appearance  at  that  time 
is  both  significant  and  interesting;  significant  in  showing 
the  efficiency  of  the  beds  but  two  colonies  having  been 
found  one  coming  from  each  bed,  at  an  interval  of  five 
days  from  each  other,  which  would  seem  to  indicate  that 
the  germs  were  present  in  very  small  quantities  and  that 
the  beds  are  about  equal  from  the  standpoint  of  efficiency. 

It  is  interesting  from  the  fact  that  it  presumably  found 
its  way  into  the  sewage  by  washing  petri  dishes  contin¬ 
ually  in  a  sink  in  the  laboratory  which  empties  into  the 
sewer.  The  original  culture  having  been  obtained  at 
Marshalltown  about  the  middle  of  March,  1900.  This  one 


-  18- 


example  gives  sufficient  evidence  of  the  possibility  of  the 
transmission  of  disease  germs  by  means  of  water,  and 
especially  sewage. 

One  question  which  presents  itself  on  the  accompany¬ 
ing  data  is  the  wide  degree  of  fluctuation  in  the  number 
of  germs  per  c.c.  found  in  the  effluent. 

Take  for  example  the  results  from  June  1,  1900  to  June 
15th,  inclusive.  The  number  of  bacteria  to  the  c.c.  ranged 
from  sixty  on  June  1st  to  15,800  on  June  15th.  Why  this 
difference?  After  considerable  research  and  observation 
it  seems  that  at  least  three  factors  would  largely  deter¬ 
mine  the  number  of  bacteria  to  the  c.c.  present  at  any  par¬ 
ticular  time.  Perhaps  of  primary  importance  is  the 
temperature  of  the  sewage  and  thus  indirectly  of  the  soil 
through  which  it  is  filtered,  and  the  air.  It  is  a  well  rec¬ 
ognized  fact  that  the  warmer  the  sewage  up  to  a  certain 
point  the  faster  the  division  of  bacteria  takes  place,  hence 
a  larger  number  of  germs  would  be  found  in  warm  sewage 
and  during  warm  weather.  Take  the  result  for  June  1, 
1900  the  air  was  82  degrees  Fahrenheit,  the  sewage  69 
degrees  and  the  number  of  germs  per  c.c.  is  60.  The  fol¬ 
lowing  day,  June  2nd,  the  air  is  one  degree  cooler  and  the 
water  the  same  temperature,  yet  there  are  1,200  bacteria 
to  the  c.c.  Take  from  the  first  of  June  to  the  11th  and 
although  the  temperature  of  the  sewage  is  constant  the 
number  of  germs  per  c.c.  fluctuates  from  60  to  15,800.  The 
soil  temperature  for  June  11th  was  69  degrees.  As  the 
soil  temperatures  have  been  taken  but  once  a  week  it  is 
impossible  to  give  its  variations  in  temperature  from  day 
to  day. 

Second,  the  condition  of  the  sewage-  to  be  purified  will 
determine  to  a  very  great  degree  the  number  of  bacteria 
to  the  c.c.  but  by  comparison  of  the  data  it  will  be  seen 
that  this  does  not  offer  a  satisfactory  explanation  in  itself. 
Take  for  instance  the  results  for  November  14,  1899  as 
compared  with  those  of  June  19,1900.  While  the  num¬ 
ber  of  bacteria  to  the  c.c.  in  the  effluent  varies  only  by  400 
(November  14,  1899,  4,500.  June  19,  1900,  4,100)  the  num¬ 
ber  of  germs  in  the  raw  sewage  varies  some  five  and  one- 
17 


— 19 


third  millions  to  the  c.c.  If  this  were  the  principal  cause 
of  fluctuation  the  effluent  of  November  14th  should  con¬ 
tain  about  41,000  bacteria  to  the  c.c.  other  things  being 
equal. 

Along  with  the  above  the  amount  of  organic  matter 
present  would  have  a  considerable  influence,  as  it  would 
serve  as  food  for  the  bacteria.  Hence  fission  would  be 
more  rapid  and  the  number  of  bacteria  to  the  c.c. 
increased,  but  no  data  bearing  on  this  point  are  at  hand. 

The  third  factor  would  be  the  time  of  taking  the 
samples,  whether  at  the  beginning  or  toward  the  end  of 
the  discharge.  It  is  presumed  that  during  the  period  that 
the  bed  is  resting  the  bacterial  life  increases;  accumulat¬ 
ing  in  the  interstices  between  the  material  of  which  the 
filter  is  composed.  When  the  discharge  comes  on  the 
beds  the  pressure  and  hence  the  force  being  greater  at 
that  time  than  at  any  other,  also  the  number  of  the  bac¬ 
teria  in  the  interstices  being  greatest  then,  might  not  the 
force  of  the  sewage  wash  these  bacteria  free  and  hence 
through  the  bed  into  the  effluent?  If  such  be  the  case  the 
number  of  bacteria  to  a  c.c.  would  be  greatest  at  the 
beginning  of  the  discharge  and  least  at  the  end.  While  I 
have  not  been  able  to  make  experiments  to  fully  elucidate 
this  point  I  feel  quite  confident  from  numerous  observa¬ 
tions  in  taking  samples  that  such  may  be  the  case. 

Of  course  all  of  these  factors  and  probably  others  acting 
in  unison  complicate  the  problem  to  such  an  extent  that 
until  more  data  is  at  hand  it  will  be  impossible  to  accu¬ 
rately  determine  the  exact  amount  of  variation  caused  by 
each  factor. 

By  referring  to  the  tables  containing  the  average  num¬ 
ber  of  germs  per  c.c.  for  each  month,  of  manhole,  tank,  and 
effluent,  it  will  be  observed  that  there  is  considerable  fluct¬ 
uation.  It  will  also  be  noticed  that  the  results  for  the 
manhole,  tank,  and  effluent  decrease  on  the  whole  together. 
The  month  containing  the  lowest  average  for  the  effluent 
is  August  in  1900  as  well  as  1899.  The  largest  average  for 
the  effluent  in  1900  is  March  after  which  there  is  a  gradual 
decrease  until  September.  Several  things  must  be  taken 


-20 


into  account  in  considering  the  cause  of  these  fluctuations. 
One  is  that  during  March  and  April  there  are  greater  fluct¬ 
uations  in  temperature,  as  well  as  in  the  humidity  of  the 
atmosphere  and  it  is  possible  that  such  a  condition  might 
favor  the  rapid  multiplication  of  bacteria.  Again,  in  July 
and  August  and  the  major  part  of  June,  college  was  not  in 
session,  hence  the  sewage  was  not  so  strong.  In  a  general 
way  it  would  appear  that  the  factors  considered  in  connec¬ 
tion  with  the  fluctuations  of  the  effluent  are  applicable 
here  also. 

One  point  which  is  rather  interesting  is  that  on  different 
occasions,  (June,  July,  1900,  also  December  of  the  same 
year),  the  average  number  of  germs  to  the  c.c.  in  the  tank 
w7as  larger  than  that  of  the  manhole  for  the  same  period. 
The  explanation  of  this  seeming  inconsistency  seems  sim¬ 
ple  enough  after  taking  into  consideration  the  fact  that 
bacteria  increase  very  rapidly,  and  that  the  sewage  is 
allowed  to  collect  in  the  tank  until  20,000  gallons  have 
been  accumulated,  when  it  is  discharged  automatically  by 
a  Miller’s  Automatic  Siphon.  Now,  if  the  flow  in  the  tank 
is  slow  (which  is  often  the  case)  for  any  reason,  the  water 
stands  longer,  and  hence  more  time  is  given  the  bacteria 
to  multiply. 

It  must  be  borne  in  mind  that  the  environment  ill  the 
tank  is  especially  favorable  for  the  rapid  production  of  bac¬ 
teria  as  there  is  an  abundance  of  organic  matter  present, 
while  the  tank  being  closed  wrould  tend  to  raise  the  tem¬ 
perature  of  the  sewage  rather  than  to  lower  it,  which 
would  further  facilitate  the  rapid  development  of  germ 
life.  Leone’s  experiments  on  the  preserving  of  the  Mang- 
fall  wTater  shows  very  clearly  what  might  be  expected  from 
letting  sewage  accumulate  slowly  in  the  tank.  It  takes 
some  times  seventeen  to  twenty  hours  and  even  longer  for 
the  tank  to  fill.  Below  are  given  the  tabulated  results  of 
his  experiments  together  with  some  similar  observations 
made  by  Cramer  on  the  water  from  the  Lake  of  Zurich. 


—  21  — 


leone’s  observations. 

No.  of  Micro-organisms 
in  one  CC.  of  water. 

Water  at  time  of  collection  contained .  5 

Water  after  standing  twenty-four  hours  in'sterilized  flask  ioo 

,  .Water  after  standing. two  days  in  sterilized  flask.  . .  ....  10,500 

Water  after  standing  three  days  in  sterilized  flask .  67,000 

Water  after  standing  four  days  in  sterilized  flask .  315,000 

Water  after  sfaridingfive  days  in  sterilized  flask . More  than  one-half  million 

gramer’s  observations. 

Hours  and  days  during  which  Number  of  Micro-organisms 

the  water  was  preserved.  in  one  CC.  of  water. 

0  hours  .  143 

24  hours .  12,457 

3  days.,..  . .  328,543 

8  days .  233,452 

17  days .  17,436 

70  days .  . . 2,500 

The  work  along  these  lines  on  the  college  sewage  may 
be  said  to  have  just  begun,  and  future  experiments  and 
data  will  materially  assist  in  the  intelligent  interpretation 
of  the  results  obtained  during  the  last  year. 


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The  Principles  of  Bacteriology . .-.543.96  1897 

2.  Adams,  Julius  W. — 

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3.  Barwise,  Sidney— 

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Sewage  Disposal  of  the  United  States . 598.7.  116  1893 

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•  8.  Davis,  Floyd— 

Report  of  Investigation  of  the  Marshalltown  Water  Supply.  .Paper 

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10.  Folwell,  A.  Prescott— 

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11.  Frankland,  Percy  and  C  C.— 

Microorganisms  in  Water . . 

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Drainage  and  Sewage  of  Buildings . 302.97  1894 

13.  Iowa,  Report  of  the  State  Board  of  Health . 591.30  1889 

14.  Iowa,  Report  of  the  State  Board  of  Health .  1899 


—  22 


15.  Kinnicutt,  L.  P. — 

Sewer  Gas  and  Some  Mistaken  Ideas  Concerning  It . . 

16.  Kinnicutt,  L.  P. — 

English  Experiments  on  the  Bacteriological  Treatment  of 
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17.  Klamperer,  P.  and  Levy,  E. — 

Clinical  Bacteriology . . . .  441.89  1900 

18.  Levy,  E.  and  Klamperer,  P.— 

Clinical  Bacteriology . . . . . . . 441.89  1900 

19.  Marston,  A.  Pammel  L.  H.  and  Weems,  J.  B. — 

Iowa  State  College  Sewage  System. — Contr.  Iowa  State 
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21.  Mason,  Wm. — 

Water  Supply . . . 477.29.1m.  1897 

22.  Massachusetts  Report  of  State  Board  of  Health,  1890. 

23.  Nichols,  W.  R. — 

Water  Supply  from  a  Chemical  and  Sanitary  Standpoint . 

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24.  Pammel,  L.  H.  Weems,  J.  B.  and  Marston,  A. — 

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25.  Pammel,  Emma  and  Pammel,  L.  H. — 

Separate  aus  dem  Centralblatt  fur  Bakteriologie,  Parasiten- 
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I 


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628.2  W15  C001 

Bacteriological  Investigation  of  the  low 


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